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Contact lenses are widely used for vision correction and cosmetic purposes. Smart contact lenses offer further opportunities as functionalized non-invasive devices capable of simultaneous vision correction, real-time health monitoring and patient specific drug delivery. Herein, a low-cost vat photopolymerization technique is developed for directly 3D printing functionalized structures on commercially available contact lenses. The process enables controlled deposition of functionalized hydrogels, in customizable patterns, on the commercial contact lens surface with negligible optical losses. Multi-functional contact lenses can also be 3D printed with multiple materials deposited at different regions of the contact lens. Herein, the functionalities of colour blindness correction and real-time UV monitoring are demonstrated, by employing three suitable dyes incorporated into 2-hydroxyethyl methacrylate (HEMA) hydrogel structures printed on contact lenses. The results suggest that 3D printing can pave the way towards simple production of low-cost patient specific smart contact lenses. [ABSTRACT FROM AUTHOR]

Color blindness or color vision deficiency (CVD) is a congenital ocular deficiency that hampers patients' daily life activities. CVD patients rely mostly on using wearable visual aids that enhance color distinction by blocking problematic wavelengths of light. Contributing to that, this study examines the fabrication of 3D‐printed colored contact lens for color blindness management. A vat photopolymerization based 3D printing technology is utilized to fabricate the contact lenses for CVD patients. An in‐house prepared resin is mixed with a low‐cost colored ink to attain the desired blocking range (520–580 nm). The fabricated lens blocks more than 50% of light at the problematic wavelengths, along with exhibiting minimal leakage when stored and examined in water and contact lens storage solution. Average contact angle and water content values are 48° and 56%, respectively. Mechanical properties demonstrate the physical adequacy of the contact lens. The CVD filtering efficacy of the tinted contact lens and its potential as a CVD wearable is evaluated by comparing its optical performance with that of commercial products. Finally, cytotoxicity analysis of the lens to dermal fibroblast cells reveals the biocompatibility of the lens as the cell viability remains greater than 75% after 24 h. [ABSTRACT FROM AUTHOR]

Additive manufacturing has revolutionised the production of intricate and complex structures, offering numerous applications across diverse industries. Among the additive manufacturing techniques, VAT photopolymerisation (VP) is a promising method for fabricating intricate structures with smooth surface finishes. However, the inherent limitations of 3D printed structures, such as compromised mechanical strength and conductivity, necessitate the incorporation of filler materials. Graphene, a remarkable two-dimensional carbon material renowned for its exceptional mechanical and electrical properties, emerges as a highly desirable filler of various applications. The review addresses the critical parameters that affect the quality and properties of graphene composites fabricated using VP, including the choice of photopolymer resin, exposure parameters, and pre and post-processing techniques. It also explores the functionalisation of graphene materials, multi-material printing and hybrid composite systems. The resulting graphene composites find applications in various fields, including electronics, aerospace, biomedicine and energy storage. This review presents a comprehensive survey of these applications, highlighting the unique advantages of VP-derived graphene composites. The challenges and future prospects in the field of VP for graphene composites are discussed. These encompass improving printability, achieving enhanced graphene dispersion, and exploring novel hybrid materials and innovative applications. [ABSTRACT FROM AUTHOR]

The benefits of enclosing pH sensors into wound dressings include treatment monitoring of wounded skin and early detection of developing chronic conditions, especially for diabetic patients. A 3D printed re-entrant auxetic hydrogel wound dressing, doped with pH indicator phenol red dye, was developed and characterized. The re-entrant auxetic design allows wound dressing adhesion to complex body parts, such as joints on arms and legs. Tensile tests revealed a yield strength of 140 kPa and Young's modulus of 78 MPa. In addition, the 3D-printed hydrogel has a swelling capacity of up to 14%, limited weight loss to 3% in six days, and porosity of near 1.2%. A reasonable pH response resembling human skin pH (4–10) was obtained and characterized. The integration of color-changing pH indicators allows patients to monitor the wound's healing process using a smartphone. In addition to the above, the mechanical properties and their dependence on post-processing were studied. The results show that the resin composition and the use of post-treatments significantly affect the quality and durability of the wound dressings. Finally, a poly (acrylic acid) (PAA) and water-based adhesive was developed and used to demonstrate the performance of the auxetic wound dressing when attached to moving body joints. [ABSTRACT FROM AUTHOR]

Additive manufacturing processes are capable of fabricating optical devices, including the production of contact lenses, waveguides, and Fresnel lenses used in a variety of applications. This study presents a novel fabrication method for high‐quality Fresnel lenses through a vat photopolymerization 3D printing method. Here, the 3D printing process is integrated with the micro/nanostructure fabrication to produce 3D optical components with imprinted micro/nanostructures in a single step. This straightforward approach allows imprinting a micro‐pattern (5 μm features size) onto the flat surface of a 3D‐printed Fresnel lens, achieve light focusing properties along with holographic rainbow effects. The printed lenses achieve focal lengths within ≤8 mm deviation from the predicted values. Such holographic Fresnel lenses are highly desirable in imaging‐based miniature spectrometers for mechanoluminescence sensoring. Thus, the masked stereolithography (MSLA) based 3D printing process can produce normal and holographic Fresnel lenses, vital in optical sensing and communication. [ABSTRACT FROM AUTHOR]

Additive manufacturing (3D printing) has the ability to architect structures at microscale, giving rise to the development of functional contact lenses (CLs) with inbuilt sensing capabilities. 3D printing technology enables fabrication of CLs without surface geometry restrictions. Spherical, nonspherical, symmetric, and asymmetric lenses can be manufactured in an integrated production process. Advantages of 3D printing over conventional techniques include fast and easy production, one‐step manufacturing, and no post processing such as grinding or polishing. In addition, and most significantly, 3D printing can create chambers within the wall of the lenses by taking the advantage of computer‐aided modeling and layer‐by‐layer deposition of the materials. These inbuilt chambers can be used for loading drugs and sensing elements. The computer‐aided design modeling can allow for manufacturing of patient‐specific CLs. This article focuses on the 3D‐printing approaches and the challenges faced in fabricating CLs. 3D‐printing technology as a technique for manufacturing of CLs is discussed, in addition to the manufacturing challenges and the possible solutions to overcome the obstacles. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) is a widely used additive manufacturing process that can be used for printing of intricate three dimensional (3D) metallic structures. Here we demonstrate the fabrication of titanium alloy Ti–6Al–4V alloy based 3D meshes with nodally-connected diamond like unit cells, with lattice spacing varying from 400 to 1000 microns. A Concept Laser M2 system equipped with laser that has a wavelength of 1075 nm, a constant beam spot size of 50μm and maximum power of 400W was used to manufacture the 3D meshes. These meshes act as optical shutters / directional transmitters and display interesting optical properties. A detailed optical characterisation was carried out and it was found that these structures can be optimised to act as scalable rotational shutters with high efficiencies and as angle selective transmission screens for protection against unwanted and dangerous radiations. The efficiency of fabricated lattice structures can be increased by enlarging the meshing size. [ABSTRACT FROM AUTHOR]

Wounds are a major health concern affecting the lives of millions of people. Some wounds may pass a threshold diameter to become unrecoverable by themselves. These wounds become chronic and may even lead to mortality. Recently, 3D printing technology, in association with biocompatible hydrogels, has emerged as a promising platform for developing smart wound dressings, overcoming several challenges. 3D printed wound dressings can be loaded with a variety of items, such as antibiotics, antibacterial nanoparticles, and other drugs that can accelerate wound healing rate. 3D printing is computerized, allowing each level of the printed part to be fully controlled in situ to produce the dressings desired. In this review, recent developments in hydrogel-based wound dressings made using 3D printing are covered. The most common biosensors integrated with 3D printed hydrogels for wound dressing applications are comprehensively discussed. Fundamental challenges for 3D printing and future prospects are highlighted. Additionally, some related nanomaterial-based hydrogels are recommended for future consideration. [ABSTRACT FROM AUTHOR]

The conventional manufacturing processes for optical sensors fabrication have limitations in terms of ease of fabrication, design freedom, mechanical flexibility, cost requirements, etc. Therefore, adapting additive manufacturing (3D printing) is highly desirable because it opens up a variety of design and manufacturing possibilities. We have demonstrated that the 3D fabrication process using computer-aided design may be used to fabricate 4D functionalized photonic devices such as Fresnel lenses. We have introduced spectral color variation as the fourth dimension to 3D printed lenses in response to temperature as an external stimulus. The digital light processing (DLP) 3D printing process parameters were optimized to print the needed features with precise geometric dimensions of the lenses. Thermochromic pigment powders were mixed in the liquid monomer resins to print tinted Fresnel lenses used for selective color focusing and temperature sensing applications. The focusing ability and thermal sensing of printed lenses were assessed using customized setups that included normalized power intensity and transmission spectra measurements. Contact angle measurements were used to determine surface wettability, revealing the hydrophilic nature of the lens material. 3D printing offers custom-built optical devices and the ability to optimize the materials for both active and passive optical sensing applications, making them more promising than traditional Fresnel lenses. [ABSTRACT FROM AUTHOR]